From 68fb755c8d48350ef5d62ca31e7a3355be60bf63 Mon Sep 17 00:00:00 2001
From: hcduan <hcduan@tencent.com>
Date: Tue, 19 Nov 2024 20:37:44 +0800
Subject: [PATCH] [bugfix] Incorrect last_update time of innodb_index_stats

Problem:
========
  When adding a new index, the statistics for the new index are
  triggered, generating a new index statistics entry. At this
  point, other indexes have not been triggered to update statistical
  information. However, the last update time for all existing indexes
  in the table's index statistics is also being refreshed, which can
  be misleading when troubleshooting issues.

Solution:
=========
  Fix the code bug to ensure that updating one index does not affect
  the statistics of other indexes.
---
 mysql-test/r/index_last_update_time.result |  8 ++++++++
 mysql-test/t/index_last_update_time.test   | 18 ++++++++++++++++++
 storage/innobase/dict/dict0stats.cc        |  4 ++--
 3 files changed, 28 insertions(+), 2 deletions(-)
 create mode 100644 mysql-test/r/index_last_update_time.result
 create mode 100644 mysql-test/t/index_last_update_time.test

diff --git a/mysql-test/r/index_last_update_time.result b/mysql-test/r/index_last_update_time.result
new file mode 100644
index 00000000000..e6ed3757139
--- /dev/null
+++ b/mysql-test/r/index_last_update_time.result
@@ -0,0 +1,8 @@
+create table t1 (c1 int primary key,c2 int ,c3 int, index idx1(c2));
+insert into t1 values (1,1,1),(2,2,2),(3,3,3),(4,4,4);
+analyze table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+alter table t1 add key idx2(c3);
+include/assert.inc [current last_update equal to the value saved before.]
+drop table t1;
diff --git a/mysql-test/t/index_last_update_time.test b/mysql-test/t/index_last_update_time.test
new file mode 100644
index 00000000000..4e6f469eb4e
--- /dev/null
+++ b/mysql-test/t/index_last_update_time.test
@@ -0,0 +1,18 @@
+create table t1 (c1 int primary key,c2 int ,c3 int, index idx1(c2));
+
+insert into t1 values (1,1,1),(2,2,2),(3,3,3),(4,4,4);
+
+analyze table t1;
+
+# Save value of 'last_update_time' before alter new index
+--let $last_update_time= `select last_update from mysql.innodb_index_stats where table_name = 't1' and index_name = 'PRIMARY' and stat_name = 'n_diff_pfx01'`
+
+sleep 2;
+
+alter table t1 add key idx2(c3);
+
+--let $assert_text= current last_update equal to the value saved before.
+--let $assert_cond= [select count(*) from mysql.innodb_index_stats where table_name = "t1" and index_name = "PRIMARY" and stat_name = "n_diff_pfx01" and last_update = "$last_update_time"] = 1
+--source include/assert.inc
+
+drop table t1;
\ No newline at end of file
diff --git a/storage/innobase/dict/dict0stats.cc b/storage/innobase/dict/dict0stats.cc
index b8c2b6b0d9a..b9522c27e0e 100644
--- a/storage/innobase/dict/dict0stats.cc
+++ b/storage/innobase/dict/dict0stats.cc
@@ -2560,8 +2560,8 @@ dberr_t dict_stats_save(dict_table_t *table_orig,
     index = it->second;
 
     if (only_for_index != nullptr &&
-        index->space != only_for_index->m_space_id &&
-        index->id != only_for_index->m_index_id) {
+        (index->space != only_for_index->m_space_id ||
+         index->id != only_for_index->m_index_id)) {
       continue;
     }
 
-- 
2.30.1